Laryngeal mask airway

Abstract

A laryngeal mask airway has a main tubular shaft ( 1 ) with a mask portion ( 5 ) attached at its patient end ( 3 ). The mask portion ( 5 ) comprises a mount ( 50 ) and a sealing cuff ( 60 ) attached to the mount. The interior of the mount ( 50 ) defines a large volume atrium ( 54 ) communicating with the bore of the shaft ( 1 ) at one end and with an opening ( 61 ) through the cuff ( 60 ) at its other end. The join between the shaft ( 1 ) and the mount ( 50 ) is located above the rear part ( 63 ) of the cuff ( 60 ). The height of the atrium ( 54 ) is between 2.5 and 3.5 the internal diameter of the shaft. The volume of the atrium ( 54 ) is such that the ratio of the internal diameter of the shaft cubed to the internal volume of the atrium is between 50 and 68.

1. A laryngeal mask airway consisting of a tubular portion and a mask portion at a patient end of the tubular portion having an inflatable sealing cuff of generally oval shape with no partition therein defining an opening within a center thereof and adapted to seal with patient tissue around the laryngeal inlet, the mask portion defining a chamber extending from the opening to the patient end of the tubular portion where the tubular portion opens directly into the chamber such that the entire chamber is available for receiving patient tissue, characterized in that the patient end of the tubular portion is located above and to the rear of the rear side of the opening such as to space it away from the epiglottis. 
   
   
     2. An airway according to  claim 1 , characterized in that the patient end of the tubular portion is located substantially midway across the width of the rear side of the sealing cuff. 
   
   
     3. An airway according to  claim 1 , characterized in that the tubular portion is a separate tube bonded into a collar on the mask portion. 
   
   
     4. An airway according to  claim 1 , wherein the chamber has a roof, characterized in that the longitudinal center line along the internal surface of the roof of the chamber is substantially straight. 
   
   
     5. An airway according to  claim 1 , characterized in that the height of the chamber is between 2.5 and 3.5 the internal diameter of the tubular portion. 
   
   
     6. An airway according to  claim 1 , wherein the chamber has a volume, characterized in that the ratio of the internal diameter of the tubular portion cubed to the volume of the chamber is between 50 and 68. 
   
   
     7. An airway according to  claim 2 , characterized in that the tubular portion is a separate tube bonded into a collar on the mask portion. 
   
   
     8. A laryngeal mask airway consisting of a tubular portion and a mask portion at a patient end having an inflatable sealing cuff of generally oval shape with no partition therein defining an opening within a center thereof and adapted to seal with patient tissue around the laryngeal inlet, the mask portion defining a chamber whereto the patient end of the tubular portion opens directly into, characterized in that the height of the chamber available for receiving patient tissue is between 2.5 and 3.5 the internal diameter of the tubular portion, and characterized in that the patient end of the tubular portion is located above and to the rear of the rear side of the opening such as to space it away from the epiglottis. 
   
   
     9. An airway according to  claim 7 , characterized in that the height of the chamber is between 2.96 and 3.27 the internal diameter of the tubular portion.